Quantcast Uses

Order this information in Print

Order this information on CD-ROM

Download in PDF Format

     

Click here to make tpub.com your Home Page

Page Title: Uses
Back | Up | Next

Click here for a printable version

Google


Web
www.tpub.com

Home


   
Information Categories
.... Administration
Advancement
Aerographer
Automotive
Aviation
Combat
Construction
Diving
Draftsman
Engineering
Electronics
Food and Cooking
Math
Medical
Music
Nuclear Fundamentals
Photography
Religion
USMC
   
Products
  Educational CD-ROM's
Printed Manuals
Downloadable Books
   

 

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Back
Lens Bench (cont)
Up
TM-9-254 Gearcase Transfer M548 M548A1 (
Next
Uses (cont)
TM 9-254 10-10. Lens Bench - Continued (2) Back  focal  length.    The  lens  to  be  tested  is  mounted  in  the  chuck  of  the  nodal  slide,  using  a  light clamping pressure to avoid straining the lens, and the azimuth of the  chuck  is  adjusted  to  0.    A  mark with crayon is placed at center of the surface  of  the  lens  facing  microscope.    Then  the  microscope  is focused on the mark as sharply as possible and the location of microscope on the ways of the bench is read by means of the vernier and scale.  The next step is to move the microscope along the ways until it is focused on the image of the target.  The new location of the microscope on its ways is read on the scale, again using the vernier.  The difference between this reading and the reading previously obtained is the back focal length of the lens. (3) Spherical aberration.  Spherical aberration can be measured by recording the difference between vernier scale settings of the observing microscope when focused on the image of target in the central area of the lens and again when focused on the image of the target in the outer annular area of the lens.  When focusing on the center of the lens, the outer annular area is covered with a ring of opaque paper.  When focusing on the outer annular area of the lens, the central area is covered with a circular disk of opaque paper. (4) Chromatic  aberration.    Chromatic  aberration  may  be  measured  by  illuminating  the  image  of  the  target with light of a known wave length (using a filter for this purpose), focusing the microscope on the image, and reading the position of microscope on the scale.  The process is repeated with different filters.  The variation of the different scale positions of the microscope will give the effect of chromatic aberration of the lens with respect to the particular wave lengths used. (5) Astigmatism.    Astigmation  can  be  measured  by  noting  the  difference  of  the  settings  of  the  observing microscope  on  the  vernier  scale,  when  it  is  focused  separately  on  any  two  lines  of  the  image  of  the target that are perpendicular to each other. (6) Coma.    When  the  image  of  a  point  transmitted  through  a  lens  appears  comet  shaped  when  viewed through the observing microscope, the presence of coma is indicated. (7) Curvature of field.  The amount of curvature of the field is determined by measuring the change of focus required when first focusing on the image through the axial center of the lens, and then focusing on the image through the outer field of the lens. (8) Distortion.  The presence of distortion is indicated when the image of a line transmitted through a lens appears curved when viewed through the observing microscope. 10-12

Privacy Statement - Press Release - Copyright Information. - Contact Us - Support Integrated Publishing

Integrated Publishing, Inc.
6230 Stone Rd, Unit Q Port Richey, FL 34668

Phone For Parts Inquiries: (727) 493-0744
Google +